1. Field of the Invention
The present invention relates to a seat belt retractor and, more particularly, to a web sensitive seat belt retractor.
2. Description of the Prior Art
Web sensitive seat belt retractors are known. Such retractors lock to prevent seat belt withdrawal in response to withdrawal of the seat belt at a rate of acceleration above a predetermined rate. The retractor locks upon rapid belt acceleration in a withdrawal direction caused by, for example, movement of an occupant relative to a vehicle undergoing a high rate of deceleration.
A web sensitive locking retractor includes a spool on which seat belt webbing is wound. The spool rotates to permit withdrawal and retraction of the belt webbing. A ratchet is fixed to the spool and rotates with the spool. A pivotable pawl engages the ratchet to block rotation of the spool in a belt withdrawal direction. Typically, the web sensitive retractor also includes an inertia member which cannot follow acceleration of the spool undergoing rapid withdrawal of the belt, and lags behind spool rotation. Thus, the inertia member and spool rotate relative to each other. This relative rotation is used to actuate pivoting of the pawl to lock the retractor.
Web sensitive seat belt retractors generally tend to be relatively complex in structure. Thus, there remains a continuing need for improvements in the design of web sensitive seat belt retractors.